RFR: 8206187: javax/management/remote/mandatory/connection/DefaultAgentFilterTest.java fails with Port already in use [v3]

[Kevin Walls]

> Test fails occasionally due to a port clash.
> Presumably the port that was returned by Utils.getFreePort(), is no longer free.
> The test creates a ProcessBuilder with the parameters for JMX, including port number, and uses that to create a new Process.
> It should retry with a new port if we fail due to a port in use, for some limited number of attempts.
> 
> main already has some retry logic, but not working:
> it checks for an InvocationTargetException to contain a BindException, but it simply gets a BindException, thrown by TestAppRun.start().
> TestAppRun.start() runs the new process and scans for errors, but on failure its predicate has only seen the first line of a failure, so a BindException is never recognised and thrown.
> Also main does not limit the retries, and handling the port retry in main() is duplicated, for each run of the test method.
> 
> So...
> 
> Make the error-scanning predicate in TestAppRun recognise a "port in use" message and throw a BindExeption.  This is a notification to the caller that it failed, it's not the actual BindException as that was thrown in a different process.
> Make the testDefaultAgent method (the main part of the test) handle retrying with a new port, a limited number of times.

Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:

  break to terminate retry loop when succesful

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7589/files
  - new: https://git.openjdk.java.net/jdk/pull/7589/files/6cdcde8a..33649830

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7589&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7589&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7589.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7589/head:pull/7589

PR: https://git.openjdk.java.net/jdk/pull/7589